Travelling drill bit

ABSTRACT

Drill bit and drill collar assemblies for use with a drill string which assemblies can be moved up and down the drill string without the need of removing the drill string from the well hole. The drill collar assembly also is shaped, and includes elements, which together serve to prevent excessive lateral shifting of the drill string, thereby assuring the drilling of a straight well hole. This invention relates to improved drill bit and drill collar assemblies for use in combination with a drill string used in the drilling of wells, such as oil wells, for example.

Q United States Patent 1 1 111 3,729,7

Werner [4 1 Apr. 24, 1973 TRAVELLING DRILL BIT FOREIGN PATENTS ORAPPLICATIONS George Werner, Pensacola 717,994 2/1942 Germany ..l75/262[73] Assignee: Werner Industries, Inc., Pensacola,

Fl Primary Examiner-James A. Leppink 22 Filed: Nov. 30 1971Attorney-Buell, Blenko & Ziesenheim 21 Appl. No.2 203,164 [57] ABSTRACTf Application Data Drill bit and drill collar assemblies for use with adrill [63] -Continuation-in-part of Sen No. 872,070, Oct. 29. Stringwhich assemblies can be moved up and down I969, abandoned. the drillstring without the need of removing the drill v string from the wellhole, The drill collar assembly U.S-

r also haped and includcs elements together [51] III. .112") 11/00 Serveto prevent excessive lateral shifting of the drill IIQICI of Search g,thereby assuring the drilling of a gh we hole. 56] References Cited Thisinvention relates to improved drill bit and drill UNITED STATES PATENIScollar assemblies for use in combination with a drill 3,370,657 2/1968Antle 175/325 string used in the drilling of wells, such as oil wells,for

229,996 7/1880 Gail ...l75/262 example. 2,0l3,838 9/1935 Pickin....l75/262 2,506,795 5/1950 Koeln.... ....l75/262 12 Claims, 11 DrawingFigures 2,550,035 4/1951 Allen ..l75/262 a a I6 I l i at l l l l I i 68l i as l a H z 74 K5 :1: 66

, h l l l I, l-r. 78 70 g. l l 7o 72 l E g 7 I l r l- 1' l l I l r I g im 4 l l s l 4 l 1 l 7 l A 1 l i a4 l l yr 84": l r v I -1 l i e I g l Xg l l E 48| L7 47* r' e2 V i c 1 I H l l l l i Y l l 1 40 I I 1: i I l ll l Patented April 24, 1973 3,729,057

4 Sheets-Sheet 1 v 62 L a4 INVENTOR Georges. Werner Patented April24,1973

4 Sheets-Sheet 2 Patented A ril24,1973 3,729,057

-4 Sheets-Sheet 3 INVENTOR George 5. Werner Patented April 24, W73

4 sheets sheet 4 TRAVELLING DRILL BIT This application is acontinuation-in-part of my copending application Ser. No. 872,070 filedOct. 29, 1969, now abandoned.

BACKGROUND Drilling a deep well, such as an oil well, is a timeconsuming, expensive operation, and is plagued with many problems. Thisinvention overcomes certain of those problems, and in order toappreciate those problems a brief description of the current method ofdrilling wells follows.

A drill bit is attached to a section of drill pipe which will passthrough a device called a rotary, and the entire drill pipe is rotated.As the well hole progresses additional drill pipe is added. The drillpipe is supported by a swivel which permits the string of pipe, (i.e.,the drill string) to rotate while allowing circulating fluid to bepumped through the pipe. The fluid acts as a lubricant and cooling agentforthe drill bit, and also serves to carry the cut rock particles toground level. Weight is required to drive the drill bit downwardly, andthis is provided by heavy pipe'attached immediately above the drill bit.This heavy pipe is referred to as a drill collar. Several sections ofdrill collar are attached to each other to provide the necessary weight.The drill collars also serve to add vertical stability to the drillstring. However, the drill string does drift away from the centerline ofthe well hole. If such drifting is not prevented the drill string willcome in contact with the side of the well hole and form an off-centerhole. Also, drifting of the drill string sometimes results in a ruptureof the drill pipe necessitating a fishing operation for the brokenparts. Fishing operations often take many. days to complete. Inaddition, an off-center hole may end up on anothers property andbeabandoned, and another well hole drilled. Aside from the problems ofabnormal operation, normal drilling has its problems. The drill bitbecomes dull after prolonged use and must be replaced. In' order to doso the entire drill string must be withdrawn from the well hole, witheach section of pipe being disconnected as it reaches the groundsurface. The drill bit is then replaced, and the drill pipe isre-connected and lowered into the well hole. In addition, thecirculating liquid system must be shut down while drill bit replacementoperation is being carried on. Shutting down the circulating systemcreates additional problems, especially in maintaining the fluidity ofthe circulating liquid.

SUMMARY OF THE INVENTION I overcome the above-mentioned problems ofdrill string drifting and drill bit replacement by my present invention.In the preferred form of the invention, I start by attaching a keyinghead to a conventional piece of drill pipe, the keying head beingpreferably square in cross-section. A two section drill bit assembly isplaced over the drill pipe with the bit assembly being free to travel upand down the drill pipe. The lower half of the drill bit assembly, orthe cutting head section, has bits fixed to the lower end thereof andthe bits are arranged so that the cutting head section is free to travelover the drill pipes. The inner surface of the cutting head is also,preferably, square in cross-section and fits snugly on the keying headfor rotation therewith. The upper section of the drill bit assembly, orthe back-up section, is

separated from the cutting head section by a thrust bearing. Thus, thecutting head section will rotate with the drill string while the back-upsection remains stationary. Holding means are provided between thecutting head and back-up sections for holding-them axially togetherwhile permitting the cutting head section to rotate. After both sectionsof my drill bit assembly are placed over the drill pipe, a first sectionof drill collar also embodying my present invention is put in place ontop of the back-up section. My drill collars include, preferably,identical longitudinal half sections pivotably connected to each other.The closed drill collar is generally square in cross-section and has adiagonal dimension slightly smaller than the diameter of the well hole.The inside diameter of the drill collar is slightly larger than theoutside diameter of the drill pipe, and thus can be readily movedupwardly and downwardly of the drill pipe. The close fit of the drillcollars in the well hole serves to maintain the drill string centered inthe well hole, thereby preventing the drift mentioned earlier andassuring a straight well hole. Stabilizers are also mounted on my drillcollars and will contact the wall of the well hole in such a manner thatthe drill collar will remain truly centered in the well hole. Thus,additional insurance is provided against drill string drift. In oneform, the stabilizers are a plurality of rollers urged outwardly bysprings or the like. The drill collar will, accordingly, be able to bemoved upwardly and downwardly in the well hole while always remainingcentered. The drill bit and collar assemblies also include means forattaching power driven lifting means for lifting or lowering the cuttinghead and backup sections, together with the drill collars, out of orinto the well hole as desired. On form of the lifting means is a pair ofcables or chains reeved over various pulleys, with one end of each cablebeing connected to the back-up section and the other end being connectedto a motor driven winch, or the like. Since the back-up section issecured to the cutting head section and is below the drill collars,pulling on the back-up section will lift all of the drill collar,cutting head section and back-up section. Thus, drill bits can bereplaced without any need to withdraw the drill string. In addition, thecirculating liquid system can continue to operate during any drill bitchange.

Other details and advantages of my present invention will becomeapparent as the following description of a present preferred embodimentthereof proceeds.

In the accompanying drawings I have shown certain present preferredembodiments of the invention, in which:

FIG. 1 is a view showing, diagrammatically, a rotary drilling rig withthe drill string thereof in a well hole, and showing the presentinvention in position during drilling;

FIG. 2 is an enlarged longitudinal elevational view through the firstsection of drill pipe forming the drill string of FIG. 1, showing insection the elements forming an embodiment of the present invention;

FIG. 3 is a view taken along the line III-III of FIG. 2; FIG. 4 is aview taken along the line IV-IV of FIG.

FIG. 5 is a view taken along the line VV of FIG. 2;

FIG. 6 is a view taken along the line VI-VI of FIG.

FIG. 7 is a perspective view showing the back-up and cutting headsections forming part of the drill bit assembly of the presentinvention;

FIG. 8 is a perspective view of part of the drill collar assemblyof thepresent invention;

FIG. 9 is an end view of the cutting head section of the drill bitassembly showing an arrangement of the drill bit; and

FIG. 10 is a perspective view of the keying head forming part of thepresent invention.

FIG. 11 is an enlarged longitudinal section showing a modification ofthe apparatus in FIG. 2 in which a down hole motor is used to rotate thekeying head and drill bit.

Referring now to the drawings wherein like reference numerals refer tolike parts throughout the various views, FIG. 1 shows, diagrammatically,a rotary rig with its mast and other operating equipment, and drillstring 10 and drill bit assembly 12 in a well hole. The operatingequipment of the rotary rig are standard and wellknown and do not formpart of the present invention. The present invention relates to thedrill bit assembly 12 and the drill collars 14 disposed on the drillstring 10 above the drill bit assembly.

As shown in FIG. I, the drill string 10 is formed of a series ofelongated tubular drill pipes 16 longitudinally aligned and fixed to oneanother by well-known threaded connections. FIG. 2 shows the lowermostdrill pipe 16 having threadably attached to the lower end thereof anelongated tubular keying head 18 having a generally squarecross-sectional shape. The drill bit assembly 12 is shown in FIG. 2 inplace ready for drilling. The drill bit assembly 12 includes a cuttinghead section 20 and a back-up section 22 disposed above the cutting headsection. The cutting head section 20 includes an elongated generallycylindrically shaped tubular body 24 with its interior bore 25 having alower section 26 formed generally square in cross-section from its lowerend up to an intermediate point thereof. The outer surface of body 24 isprovided with four uniformly spaced longitudinally extending scallops 28for the upward passage of circulating fluid, rock chips, and the like.The upper section 27 of the bore 25 is circular in cross-section and hasa diameter slightly greater than the outside diameter of the drill pipes16 so that the cutting head section 20 can readily slide over thesurface of the drill pipes 16. Lower section 26 of bore 25 is sized tofit snugly on keying head 18 and yet provides enough clearance for thecutting head section 20 to slide on or off the keying head. As shown inFIG. 9, a series of drill bits 30 are suitably attached about the lowerend of cutting head section 20. The pattern of the drill bits 30 issuitable for drilling rock formations in forming a well hole.

A retractable drill bit 31 is disposed centrally of the lowerend ofcutting head section 20 to provide a 360 cutting surface. As shown inFIGS. 2 and 9, the retractable drill bit 31 is arranged to permit thecutting head section 20 to move longitudinally upwardly or downwardly ofthe drill string. The retractable drill bit 31 is suitably fixed to aplate member 32 pivotably mounted on the lower end of cutting headsection 20, as by a suitable hinge 34. The plate member 32 is biasedtoward the lower end of cutting head section 20 by a suitable spring notclearly shown. A plurality of passageways 38 extends through platemember 32 and communicates with the bore 25 of body 24. Thesepassageways 38 serve to direct circulating fluid onto the drill bits 30and 31, which circulating fluid is pumped through the hollow drillstring 10 from a pumping station on ground level.

A circumferential groove 40 is formed in the upper end portion of thebody 24 of cutting head section 20. As will be more clearly describedhereinafter, groove 40 serves as part of the holding means for axiallysecuring cutting head section 20 with back-up section 22.

Back-up section 22 is disposed above cutting head section 20, andincludes an elongated generally cylindrically shaped tubular body member42. The outer surface of body member 42 is provided with fourlongitudinally extending scallops 46 for the upward passage ofcirculating fluid, rock chips, and the like. Body member 42 is formed oftwo longitudinal semicylindrical sections 42a and 42b, shown inperspective in FIG. 7. The two sections 420 and 4212 are provided withsuitably arranged ears 43 which allow the sections to be mated with eachother in a hinged relationship. The ears 43 are provided withlongitudinal coaxial openings 44 suitably sized to receive a hinge pin45. When the sections 42a and 42b are closed about a drill pipe 16 ahinge pin 45 is inserted through the formerly separated ears to thusprovide a means for locking the back-up section 22 around the drillstring 10. The bore 47 through the body member 42 of back-up section 22is divided into an upper portion 48 having a diameter slightly greaterthan the outside diameter of the drill pipe 16, and a lower portion 49larger in diameter than upper portion 48, thereby defining a shoulder 50therebetween. A radially inwardly extending lip 52 is formed at thelower end of the body member 42 of back-up section 22. Lip 52 issuitably sized to loosely fit into groove 40 to thereby axially securethe back-up section 22 to the cutting head section 20. As shown in FIG.2, there is a slight axial clearance between lip 52 and groove 40 topermit a small axial movement between the back-up and cutting headsections. When I use the expression axially secured herein with regardto the back-up and cutting head sections it means that the sections areheld axially together with a slightly loose fit between the lip 52 andgroove 40. The loose fit is desirable for ease of attaching the back-upsection to the cutting head section. The lip 52 and groove 40 are alsosuitably sized so that the cutting head section 20 is able to rotatewith respect to back-up section 22 when the drill string 10 is rotated.A thrust bearing 54 of any well-known type is interposed between theback-up section 22 and cutting head section 20 in abutment with theupper end surface of the cutting head section 20 and the shoulder 50 ofback-up section 22.

When the cutting head section 20 and back-up section 22 are arranged onthe drill pipe 16, the drill collars 14 are located about the drill pipe16. Each drill collar 14 includes an elongated, tubular main body 58having a generally square cross-section shape with a diagonal dimensionslightly less than the diameter of the well hole being drilled. Forexample, the diagonal dimension of the main body 58 could be about 1inch less than the diameter of the well hole. This would give about a 1%inch clearance between the well hole and the corners of the drill collarwhich clearance would be enough to permit the drill collars to be liftedout or lowered into the well hole while at the same time providing apositive centering of the drill string in the well hole. The main body58 of the drill collars is comprised of a pair of longitudinal sections58a and 58b suitably hinged to each other as by interlocking ears 59 andhinge pins 60 much in the same fashion as the hinge arrangement for thesections forming back-up section 22. When the sections 58a and 58b areclosed around a drill pipe to form main body 58 hinge pins 60 areinserted into the formerly separated ears 59 to thereby lock the mainbody around the drill string. The bore 62 is generally circular incross-section and has a diameter slightly greater than the outsidediameter of the drill pipes 16 to thereby permit the drill collars 14 tobe slid over the drill string 10. Pairs of diametrically opposedstabilizer means 66 are arranged in main body 58 of the drill collars14. As shown in FIG. 1, each face of the main body 58 has threelongitudinally spaced stabilizer means 66, thereby totaling 12stabilizer means for each drill collar 14. It may be convenient toemploy a different number or style of stabilizer means or to arrangethem in a different pattern. One of the stabilizer means 66 shownin'FlGS. 2 and 8, will be described with it being understood that suchdescription relates to all of them. The stabilizer means 66 includes apair of longitudinally extending parallel arms 70 suitably pivotablymounted by hinge pin 74 at their respective upper ends to brackets 68suitably secured to the main body 58. A pair of longitudinally spacedrollers 72 are disposed in a hollow housing 73 which in turn is suitablypivotably supported between the lower ends of arms 70. The housing 73 issuitably sized for receiving the respective rollers 72 such that aportion of the rollers extends radially outwardly of the housing. Pins76 extend through the housing 73, the rollers 72 and the arms 70 to holdthe rollers 72 in place with respect to the arms and housing. A flatspring 78 is suitably supportedby hinge pin 74 and is arranged to engagethe main body 58 and arms 70 to bias the arms 70 radially outwardly withrespect to main body 58 such that the rollers 72 contact the wall of thewell hole when the drill collars 14 are around the drill string 10. Thespring 78 is suitably selected so that the stabilizer means 66 giveswhen the drill collars 14 is moved upwardly or downwardly with respectto the drill string 10, while at the same time the stabilizer means 66maintains the drill collars 14, and in turn the drill string 10,centrally oriented with respect to the well hole.

Attachment means are provided for lifting the drill collars and drillbit assembly. One representative means for lifting or lowering thecutting head section 20, back-up head section 22, and drill collars 14is illustrated as a simple motor driven winch and cable arrangement. Apair of cables 84 extend around suitable pulleys and idlers into thewell, with one end connected to the drum of motor driven winch 86 andthe other ends suitably fixed to the upper surface of back-up section22. The cables 84 will run along the drill pipes 16 and pass throughlongitudinal slots 88 provided in the bore 62 of main body 58 of thedrill collars 14.

FIG. 4 shows a modification of the apparatus illustrated in FIG. 2 inwhich a motor is interposed in the drill string between the drill bitassembly and the top of the well. Like numbers are used to designatelike parts.

A down hole motor 89 is connected between the lowermost drill pipe 16and the keying head 18. Down hole motors are well known and producerotary motion resulting from the passage of drilling mud through themotor. If the drill string and pipe 16 are secured against rotation, themotor will rotate keying head 1% when drilling mud is pumped through themotor.

In the arrangement of FIG. 11 cables 84 are connected to pass down thewell outside of the drill collar 14.

Many modifications can be made to the present invention as those skilledin the art would readily recognize. For example, a rack and gear typelifting means could be used for raising and lowering the cutting headsection, back-up section, and drill collars; various retractable bitarrangements could be substituted for that shown and described; thedrill collar could be shaped circular in cross-section, or for thatmatter any other suitable cross-section; the drill bit arrangement neednot have a retractable bit, but can simply be provided with a centralopening of sufficient size to permit the cutting head section to slideover the drill string; the cutting bit may be replaced by a core bit forcore sampling; apparatus for logging a well may be used in conjunctionwith the invention; many various stabilizer means could be adapted tothe present invention.

In the operation of the arrangement shown in FIG. 2, the drill string isrotated, causing keying head 18 and cutting head section 20 to rotate.Drill collar 14 and back-up section 22 will not rotate but will remainsubstantially in one angular position because of the interposition ofthrust bearing 54. Circulation fluid such as drilling mud is pumped downthe drill string and will pass around the cutting bits and will carryfreshly cut rock and earth back to the surface in the conventionalmanner. When it becomes necessary to replace the drill hits, the lowerassembly is lifted by lifting cables $4. The drill bit assembly 12, andcollars M will be lifted to the surface while the drill string remainsin place. After necessary maintenance the assemblage is lowered into thewell, where cutting head section 20 may be readily located on keyinghead 18. Drilling is then resumed.

In the arrangement of FIG. 11, rotational motion of the keying head andcutting head assembly is provided by down hole motor 89 and the drillstring above motor 89 remains stationary against rotation. The drill bitassembly may be removed for maintenance and repair in the same manner aspreviously described.

In some circumstances it may be desirable not to provide a permanentconnection from the drill bit assembly and drilling collars to thelifting means. In such instances a specialized coupling or fishing toolmay be employed to raise the entire assemblage.

While I have shown and described a present preferred embodiment of thepresent invention it is to be distinctly understood that the inventionis not limited thereto but may be otherwise variously practiced withinthe scope of the following claims.

I claim:

1. A drill bit assembly for use in combination with a drill stringincluding a plurality of longitudinally aligned hollow drill pipes,comprising:

an .elongated tubular keying head member removably fixed with andlongitudinally aligned with the lowermost drill pipe in the drillstring;

drill bit housing means movable longitudinally upwardly and downwardlyof the drill string, and including a tubular cutting head sectionlongitudinally slidably arranged around said keying head member andnon-rotatable with respect thereto, and a tubular back-up sectiondisposed around a drill pipe above said cutting head section;

rotary drilling bit means fixed to the lower end surface of said cuttinghead section;

holding means on said cutting head and back-up sections for axiallysecuring said sections to each other while permitting said sections torotate with respect to each other;

bearing means operatively arranged between said sections for allowingsaid cutting head to rotate with the rotating drill string while saidback-up section remains stationary;

tubular secondary back-up members disposed around a drill pipe abovesaid back-up section of said drill bit housing means; and

attachment means operatively connected to said drill bit assembly forlifting and lowering said drill bit assembly out of and into a well.

2. A drill bit assembly as set forth in claim 1 wherein said back-uphead section is divided into longitudinal sections including at least apair of elongated body members, hinge means between adjoining bodymembers for opening and closing the body members with respect to thedrill string, and locking means for locking said body members around thedrill string.

3. A drill bit assembly as set forth in claim 1 wherein said rotarydrilling bit means includes a plurality of bits fixed about the surfaceof the lower end of said cutting head section, an elongated plate memberextending transversely across the lower end of said cutting head sectionand pivotably connected thereto, resilient means bearing said platemember against the surface of the lower end of said cutting headsection, a bit fixed to an intermediate portion of said plate member andextending downwardly with respect thereto, and said cutting head sectionhaving a plurality of passageway means extending from the interiorthereof through the lower end thereof and directed toward said bits forproviding egress for circulating fluid passing through the drill string.

4. A drill bit assembly as set forth in claim 1 wherein said holdingmeans includes a radially inwardly extending annular lip fixed to saidback-up section at the lower end thereof, a circumferential grooveformed in the end portion thereof, said lip fitting loosely into saidgroove such that said sections are axially secured to each other whilesaid sections can rotate with respect to each other.

5. A drill bit assembly as set forth in claim 1 wherein said rotarydrilling bit means includes a plurality of bits fixed about the surfaceof the lower end of said cutting head section, a central bit meansdisposed centrally on the lower end of said cutting head section andbeing retractable and extensible with respect to said cutting headsection for retracting when said cutting head section is moved upwardlyor downwardly with respect to the drill string and for extending intocutting position when said cutting head section is positioned on saidkeying head member.

6. A drill bit assembly for use in combination with a drill stringincluding a plurality of longitudinally aligned hollow drill pipes,comprising:

an elongated tubular keying head member having a generally squarecross-section removably fixed with and longitudinally aligned with thelowermost drill pipe in the drill string;

drill bit housing means moveable longitudinally upwardly and downwardlyof the drill string, and including a tubular generally cylindricallyshaped cutting head section having its interior bore formed at least inpart in a generally square crosssectional shape conforming substantiallyto the shape of said keying head member and longitu' dinally slidablyarranged on said keying head member, and a tubular back-up sectiondisposed around a drill pipe above said cutting head section andincluding a pair of semi-cylindrical body members articulated to eachother for opening and closing around the drill string;

locking means for locking said body members around the drill string;said back-up head having a radially inwardly extending annular lip, onehalf of which is on each of said body members, on the lower end portionthereof, said cutting head section having a circumferential grooveformed in the external surface thereof, said lip fitting loosely intosaid groove such that said sections are axially secured to each otherwhile said sections can rotate with respect to each other;

thrust bearing means operatively arranged between said cutting head andback-up sections for allowing said cutting head section to rotate withthe rotating drill string while said back-up section remains stationary;

rotary drilling bit means fixed to the lower end surface cutting headsection and arranged for cutting a well hole while permitting saidcutting head section to be moved upwardly and downwardly of the drillstring; and

power driven lifting means fixed with said back-up section for liftingand lowering said cutting head and back-up sections together into andout of a well.

7. A drill collar assembly for use in combination with a drill stringincluding a plurality of longitudinally aligned hollow drill pipes and adrill bit assembly having a stationary upper back-up section,comprising:

an elongated tubular body shaped to fit longitudinally slidably arounddrill pipes and having external dimensions slightly less than thediameter of the well hole being drilled such that lateral shifting ofthe drill will be prevented, said body including a plurality oflongitudinal sections articulated to each other for opening and closingaround a drill string;

locking means for locking said sections around the drill string; and

stabilizer means for positioning said body centrally of the well holesupported by said body and including a plurality of roller membersextending radially outwardly of said body, and biasing means supportedby said body and connected with said roller members outwardly of saidbody.

8. A drill collar assembly as set forth in claim 7 wherein said body haslongitudinal passageway means therethrough by receiving cables formingpart of a lifting means for lifting and lowering the drill bit and drillcollar assemblies together.

9. A drill collar assembly as set forth in claim 7 wherein said body hasa generally square cross-sectional shape with the diagonal dimensionthereof being slightly less than the diameter of the well hole beingdrilled, and said body includes a pair of longitudinal sections.

10. A drill bit assembly for use in combination with a rotatable drillstring including a plurality of longitudinally aligned hollow drillpipes and adapted to be raised and lowered into and out of a well holewithout disturbing said drill string, comprising:

drill bit housing means movable longitudinally upwardly and downwardlyof said drill string, and including:

i. a tubular cutting head section connected to the bottom portion of thelowermost section of said drill string in a manner to permit relativelongitudinal sliding motion but to prevent relative rotational motiontherebetween, and

ii. a tubular back-up section disposed around a drill pipe above saidcutting head section;

rotary drilling bit means connected to the lower portion of said cuttinghead section;

holding means on said cutting head and back-up sections for axiallysecuring said sections to each other while permitting said sections torotate with respect to each other; and

bearing means operatively arranged between said cutting head section andsaid back-up section for allowing said cutting head to rotate with therotating drill string while said back-up section remains stationary.

11. A drill bit assembly with a combination of a drill string includinga plurality of a longitudinally aligned hollow drill pipes, comprising:

a power means removably fixed longitudinally aligned with the lowermostdrill pipe and nonrotatable with respect thereto;

elongated tubular keying head member removably fixed with andlongitudinally aligned with said power means and rotatable by said powermeans; drill bit housing means movable longitudinally upwardly anddownwardly of the drill string, and including a tubular cutting headsection longitudinally slidably arranged around said keying head memberand non-rotatable with respect thereto, and a tubular back-up sectiondisposed around a drill pipe above said cutting head section;

rotary drilling bit means fixed to the lower end surface of said cuttinghead section;

holding means on said cutting head and back-up sections for axiallysecuring said sections to each other while permitting said sections torotate with respect to each other;

bearing means operatively arranged between said sections for allowingsaid cutting head to rotate with the rotating drill string while saidback-up section remains stationary; I tubular secondary back-up membersdisposed around a drill pipe above said back-up section of said drillbit housing means; and

attachment means on said back-up section of said drill bit housing andon said secondary back-up members for lifting said cutting head, back-upsection and secondary back-up members together into and out ofa well.

12. A drill collar assembly adapted for use in combination with a drillstring, said drill string comprising a plurality of longitudinallyaligned hollow drill pipes extending from the surface of the ground tothe bottom of a well and a drill bit assembly at the lower end of thedrill pipes, said drill bit assembly having a larger diameter than thedrill pipes and being vertically keyed to the lower end of the drillpipes for vertical movement of the drill bit assembly relative to thedrill pipes,

said drill collar assembly comprising an elongated hollow tube-likemember having an outside diameter smaller than the diameter of the welland an inside diameter larger than the drill pipes and the jointsthereof but smaller than the outside diameter drill bit assembly,whereby said collar may be lifted to the top of the well without liftingthe drill pipes and may be lowered to rest upon the drill bit assembly,said drill collar assembly comprising stabilizing members supported bythe tube-like member, movable radially, and biased outwardly tocontinuously engage the wall of the well, whereby said drill collarassembly is radially positioned in the well during positioning of thedrill bit assembly and during drilling.

FORM Po-mso (10-69) mnrnn snares rnrnnr orrrnis; CEETEFEQATE OF PatentNo, 3 7Z9 O57 Dated April 24 1973 lnventor(s) seorgg TIlOl" It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line .35, "On" should read One Column 8,

claim'7, line 56, after "drill" insert string Signed and sealed this26th day of February 1974.

Attest: EDWARD I LPLETCHERJR. MARSHALL DANN .Attesting Officercommiggibne'f of Patents USCOMM-DC 60376-P69 fl' u.s. GOVERNMENT PRmTmpOFFICE: (969 o-aee-azn,

ow A

1. A drill bit assembly for use in combination with a drill stringincluding a plurality of longitudinally aligned hollow drill pipes,comprising: an elongated tubular keying head member removably fixed withand longitudinally aligned with the lowermost drill pipe in the drillstring; drill bit housing means movable longitudinally upwardly anddownwardly of the drill string, and including a tubular cutting headsection longitudinally slidably arranged around said keying head memberand non-rotatable with respect thereto, and a tubular back-up sectiondisposed around a drill pipe above said cutting head section; rotarydrilling bit means fixed to the lower end surface of said cutting headsection; holding means on said cutting head and back-up sections foraxially securing said sections to each other while permitting saidsections to rotate with respect to each other; bearing means operativelyarranged between said sections for allowing said cutting head to rotatewith the rotating drill string while said back-up section remainsstationary; tubular secondary back-up members disposed around a drillpipe above said back-up section of said drill bit housing means; andattachment means operatively connected to said drill bit assembly forlifting and lowering said drill bit assembly out of and into a well. 2.A drill bit assembly as set forth in claim 1 wherein said back-up headsection is divided into longitudinal sections including at least a pairof elongated body members, hinge means between adjoining body membersfor opening and closing the body members with respect to the drillstring, and locking means for locking said body members around the drillstring.
 3. A drill bit assembly as set forth in claim 1 wherein saidrotary drilling bit means includes a plurality of bits fixed about thesurface of the lower end of said cutting head section, an elongatedplate member extending transversely across the lower end of said cuttinghead section and pivotably connected thereto, resilient means bearingsaid plate member against the surface of the lower end of said cuttinghead section, a bit fixed to an intermediate portion of said platemember and extending downwardly with respect thereto, and said cuttinghead section having a plurality of passageway means extending from theinterior thereof through the lower end thereof and directed toward saidbits for providing egress for circulating fluid passing through thedrill string.
 4. A dRill bit assembly as set forth in claim 1 whereinsaid holding means includes a radially inwardly extending annular lipfixed to said back-up section at the lower end thereof, acircumferential groove formed in the end portion thereof, said lipfitting loosely into said groove such that said sections are axiallysecured to each other while said sections can rotate with respect toeach other.
 5. A drill bit assembly as set forth in claim 1 wherein saidrotary drilling bit means includes a plurality of bits fixed about thesurface of the lower end of said cutting head section, a central bitmeans disposed centrally on the lower end of said cutting head sectionand being retractable and extensible with respect to said cutting headsection for retracting when said cutting head section is moved upwardlyor downwardly with respect to the drill string and for extending intocutting position when said cutting head section is positioned on saidkeying head member.
 6. A drill bit assembly for use in combination witha drill string including a plurality of longitudinally aligned hollowdrill pipes, comprising: an elongated tubular keying head member havinga generally square cross-section removably fixed with and longitudinallyaligned with the lowermost drill pipe in the drill string; drill bithousing means moveable longitudinally upwardly and downwardly of thedrill string, and including a tubular generally cylindrically shapedcutting head section having its interior bore formed at least in part ina generally square cross-sectional shape conforming substantially to theshape of said keying head member and longitudinally slidably arranged onsaid keying head member, and a tubular back-up section disposed around adrill pipe above said cutting head section and including a pair ofsemi-cylindrical body members articulated to each other for opening andclosing around the drill string; locking means for locking said bodymembers around the drill string; said back-up head having a radiallyinwardly extending annular lip, one half of which is on each of saidbody members, on the lower end portion thereof, said cutting headsection having a circumferential groove formed in the external surfacethereof, said lip fitting loosely into said groove such that saidsections are axially secured to each other while said sections canrotate with respect to each other; thrust bearing means operativelyarranged between said cutting head and back-up sections for allowingsaid cutting head section to rotate with the rotating drill string whilesaid back-up section remains stationary; rotary drilling bit means fixedto the lower end surface cutting head section and arranged for cutting awell hole while permitting said cutting head section to be movedupwardly and downwardly of the drill string; and power driven liftingmeans fixed with said back-up section for lifting and lowering saidcutting head and back-up sections together into and out of a well.
 7. Adrill collar assembly for use in combination with a drill stringincluding a plurality of longitudinally aligned hollow drill pipes and adrill bit assembly having a stationary upper back-up section,comprising: an elongated tubular body shaped to fit longitudinallyslidably around drill pipes and having external dimensions slightly lessthan the diameter of the well hole being drilled such that lateralshifting of the drill will be prevented, said body including a pluralityof longitudinal sections articulated to each other for opening andclosing around a drill string; locking means for locking said sectionsaround the drill string; and stabilizer means for positioning said bodycentrally of the well hole supported by said body and including aplurality of roller members extending radially outwardly of said body,and biasing means supported by said body and connected with said rollermembers outwardly of said body.
 8. A drill collar assembly as set forthin claim 7 wherein said body has Longitudinal passageway meanstherethrough by receiving cables forming part of a lifting means forlifting and lowering the drill bit and drill collar assemblies together.9. A drill collar assembly as set forth in claim 7 wherein said body hasa generally square cross-sectional shape with the diagonal dimensionthereof being slightly less than the diameter of the well hole beingdrilled, and said body includes a pair of longitudinal sections.
 10. Adrill bit assembly for use in combination with a rotatable drill stringincluding a plurality of longitudinally aligned hollow drill pipes andadapted to be raised and lowered into and out of a well hole withoutdisturbing said drill string, comprising: drill bit housing meansmovable longitudinally upwardly and downwardly of said drill string, andincluding: i. a tubular cutting head section connected to the bottomportion of the lowermost section of said drill string in a manner topermit relative longitudinal sliding motion but to prevent relativerotational motion therebetween, and ii. a tubular back-up sectiondisposed around a drill pipe above said cutting head section; rotarydrilling bit means connected to the lower portion of said cutting headsection; holding means on said cutting head and back-up sections foraxially securing said sections to each other while permitting saidsections to rotate with respect to each other; and bearing meansoperatively arranged between said cutting head section and said back-upsection for allowing said cutting head to rotate with the rotating drillstring while said back-up section remains stationary.
 11. A drill bitassembly with a combination of a drill string including a plurality of alongitudinally aligned hollow drill pipes, comprising: a power meansremovably fixed longitudinally aligned with the lowermost drill pipe andnon-rotatable with respect thereto; an elongated tubular keying headmember removably fixed with and longitudinally aligned with said powermeans and rotatable by said power means; drill bit housing means movablelongitudinally upwardly and downwardly of the drill string, andincluding a tubular cutting head section longitudinally slidablyarranged around said keying head member and non-rotatable with respectthereto, and a tubular back-up section disposed around a drill pipeabove said cutting head section; rotary drilling bit means fixed to thelower end surface of said cutting head section; holding means on saidcutting head and back-up sections for axially securing said sections toeach other while permitting said sections to rotate with respect to eachother; bearing means operatively arranged between said sections forallowing said cutting head to rotate with the rotating drill stringwhile said back-up section remains stationary; tubular secondary back-upmembers disposed around a drill pipe above said back-up section of saiddrill bit housing means; and attachment means on said back-up section ofsaid drill bit housing and on said secondary back-up members for liftingsaid cutting head, back-up section and secondary back-up memberstogether into and out of a well.
 12. A drill collar assembly adapted foruse in combination with a drill string, said drill string comprising aplurality of longitudinally aligned hollow drill pipes extending fromthe surface of the ground to the bottom of a well and a drill bitassembly at the lower end of the drill pipes, said drill bit assemblyhaving a larger diameter than the drill pipes and being vertically keyedto the lower end of the drill pipes for vertical movement of the drillbit assembly relative to the drill pipes, said drill collar assemblycomprising an elongated hollow tube-like member having an outsidediameter smaller than the diameter of the well and an inside diameterlarger than the drill pipes and the joints thereof but smaller than theoutside diameter drill bit assembly, whereby said collar may be liftedto the top oF the well without lifting the drill pipes and may belowered to rest upon the drill bit assembly, said drill collar assemblycomprising stabilizing members supported by the tube-like member,movable radially, and biased outwardly to continuously engage the wallof the well, whereby said drill collar assembly is radially positionedin the well during positioning of the drill bit assembly and duringdrilling.